Showing papers by "University of Central Florida published in 2005"

Is there a “Big Five” in Teamwork?:

Abstract: The study of teamwork has been fragmented through the years, and the findings are generally unable to be used practically. This article argues that it is possible to boil down what researchers know about teamwork into five core components that the authors submit as the “Big Five” in teamwork. The core components of teamwork include team leadership, mutual performance monitoring, backup behavior, adaptability, and team orientation. Furthermore, the authors examine how these core components require supporting coordinating mechanisms (e.g., shared mental modes, closed-loop communication, and mutual trust) and vary in their importance during the life of the team and the team task. Finally, the authors submit a set of propositions for future research.

Scholars Before Researchers: On the Centrality of the Dissertation Literature Review in Research Preparation

Abstract: A thorough, sophisticated literature review is the foundation and inspiration for substantial, useful research. The complex nature of education research demands such thorough, sophisticated reviews. Although doctoral education is a key means for improving education research, the literature has given short shrift to the dissertation literature review. This article suggests criteria to evaluate the quality of dissertation literature reviews and reports a study that examined dissertations at three universities. Acquiring the skills and knowledge required to be education scholars, able to analyze and synthesize the research in a field of specialization, should be the focal, integrative activity of predissertation doctoral education. Such scholarship is a prerequisite for increased methodological sophistication and for improving the usefulness of education research.

Understanding organization-customer links in service settings.

Abstract: We develop a framework of service-unit behavior that begins with a unit's leader's service-focused behavior and progresses through intermediate links (service climate and customer-focused organizat...

Bayesian modeling of dynamic scenes for object detection

Abstract: Accurate detection of moving objects is an important precursor to stable tracking or recognition. In this paper, we present an object detection scheme that has three innovations over existing approaches. First, the model of the intensities of image pixels as independent random variables is challenged and it is asserted that useful correlation exists in intensities of spatially proximal pixels. This correlation is exploited to sustain high levels of detection accuracy in the presence of dynamic backgrounds. By using a nonparametric density estimation method over a joint domain-range representation of image pixels, multimodal spatial uncertainties and complex dependencies between the domain (location) and range (color) are directly modeled. We propose a model of the background as a single probability density. Second, temporal persistence is proposed as a detection criterion. Unlike previous approaches to object detection which detect objects by building adaptive models of the background, the foregrounds modeled to augment the detection of objects (without explicit tracking) since objects detected in the preceding frame contain substantial evidence for detection in the current frame. Finally, the background and foreground models are used competitively in a MAP-MRF decision framework, stressing spatial context as a condition of detecting interesting objects and the posterior function is maximized efficiently by finding the minimum cut of a capacitated graph. Experimental validation of the proposed method is performed and presented on a diverse set of dynamic scenes.

The Efficacy of Play Therapy With Children: A Meta-Analytic Review of Treatment Outcomes

Abstract: The efficacy of psychological interventions for children has long been debated among mental health professionals; however, only recently has this issue received national attention, with the U.S. Public Health Service (2000) emphasizing the critical need for early intervention and empirically validated treatments tailored to children’s maturational needs. Play therapy is a developmentally responsive intervention widely used by child therapists but often criticized for lacking an adequate research base to support its growing practice. A meta-analysis of 93 controlled outcome studies (published 1953‐2000) was conducted to assess the overall efficacy of play therapy and to determine factors that might impact its effectiveness. The overall treatment effect for play therapy interventions was 0.80 standard deviations. Further analysis revealed that effects were more positive for humanistic than for nonhumanistic treatments and that using parents in play therapy produced the largest effects. Play therapy appeared equally effective across age, gender, and presenting issue.

Does Corporate Headquarters Location Matter for Stock Returns

Abstract: We document strong comovement in the stock returns of firms headquartered in the same geographic area. Moreover, stocks of companies that change their headquarters location experience a decrease in their comovement with stocks from the old location and an increase in their comovement with stocks from the new location. The local comovement of stock returns is not explained by economic fundamentals and is stronger for smaller firms with more individual investors and in regions with less financially sophisticated residents. We argue that price formation in equity markets has a significant geographic component linked to the trading patterns of local residents.

The factor structure of the presence questionnaire

Abstract: Constructing a valid measure of presence and discovering the factors that contribute to presence have been much sought after goals of presence researchers and at times have generated controversy among them. This paper describes the results of principal-components analyses of Presence Questionnaire (PQ) data from 325 participants following exposure to immersive virtual environments. The analyses suggest that a 4-factor model provides the best fit to our data. The factors are Involvement, Adaptation/Immersion, Sensory Fidelity, and Interface Quality. Except for the Adaptation/Immersion factor, these factors corresponded to those identified in a cluster analysis of data from an earlier version of the questionnaire. The existence of an Adaptation/Immersion factor leads us to postulate that immersion is greater for those individuals who rapidly and easily adapt to the virtual environment. The magnitudes of the correlations among the factors indicate moderately strong relationships among the 4 factors. Within these relationships, Sensory Fidelity items seem to be more closely related to Involvement, whereas Interface Quality items appear to be more closely related to Adaptation/Immersion, even though there is a moderately strong relationship between the Involvement and Adaptation/Immersion factors.

Information Processing View of Organizations: An Exploratory Examination of Fit in the Context of Interorganizational Relationships

Abstract: This study uses Galbraith's information processing theory to examine the fit between information processing needs and information processing capability in an interorganizational supply chain context and to examine its effect on performance. Information processing needs are assessed based on various characteristics of the product and procurement environment and information processing capabilities are assessed by the level of information technology support for various activities in the procurement life cycle. A taxonomy of information processing needs and information processing capabilities is developed. The effect of the fit between information processing needs and capabilities on procurement performance is examined. The study collected data on 142 products through personal interviews and surveys, used cluster analytic techniques to develop taxonomies, and analysis of variance (ANOVA) to test the fit between needs and capability, modeled as an interaction effect. The results reveal two clusters for information processing needs and three clusters for information processing capability. ANOVA results show that the interactive effect of information needs and capability has a significant effect on performance, supporting our fit theory.

Actions sketch: a novel action representation

Abstract: In this paper, we propose to model an action based on both the shape and the motion of the performing object. When the object performs an action in 3D, the points on the outer boundary of the object are projected as 2D (x, y) contour in the image plane. A sequence of such 2D contours with respect to time generates a spatiotemporal volume (STV) in (x, y, t), which can be treated as 3D object in the (x, y, t) space. We analyze STV by using the differential geometric surface properties to identify action descriptors capturing both spatial and temporal properties. A set of action descriptors is called an action sketch. The first step in our approach is to generate STV by solving the point correspondence problem between consecutive frames. The correspondences are determined using a two-step graph theoretical approach. After the STV is generated, actions descriptors are computed by analyzing the differential geometric properties of STV. Finally, using these descriptors, we perform action recognition, which is also formulated as graph theoretical problem. Several experimental results are presented to demonstrate our approach.

Panel LM Unit-root Tests with Level Shifts*

Abstract: This paper proposes a new panel unit‐root test based on the Lagrangian multiplier (LM) principle. We show that the asymptotic distribution of the new panel LM test is not affected by the presence of structural shifts. This result holds under a mild condition that N/T→k, where k is any finite constant. Our simulation study shows that the panel LM unit‐root test is not only robust to the presence of structural shifts, but is more powerful than the popular Im, Pesaran and Shin (IPS) test. We apply our new test to the purchasing power parity (PPP) hypothesis and find strong evidence for PPP.

Modifications of the Helbing-Molnár-Farkas-Vicsek Social Force Model for Pedestrian Evolution

Abstract: A model of crowd motion that considers each pedestrian as a Newtonian particle subject to both physical and social forces was reported by Helbing, Farkas, and Vicsek in 2000. Subsequent numerical simulations of this model, performed by its authors, showed that it exhibits realistic crowd behavior. In this article, the authors point out that numerical values of certain parameters in that model may produce counterintuitive results when applied to the motion of an isolated pedestrian or a small number of pedestrians. They have considered modifications of the original model, which allow them to use parameter values that, in the aforementioned sense, are more realistic. However, this is achieved by introducing more features and parameters into the original model. These features are described, and some results of the numerical simulations of the modified model are presented. Two major results of their study need to be mentioned. First, they developed an algorithm, based on an explicit numerical integration scheme, which prevents simulated pedestrians from overlapping with one another in physical space. Second, they demonstrated how the form of the social repulsive force between two pedestrians may be deduced from certain measured characteristics of pedestrian flows.

Semaphorin3A signalling is mediated via sequential Cdk5 and GSK3β phosphorylation of CRMP2: Implication of common phosphorylating mechanism underlying axon guidance and Alzheimer's disease

Abstract: Collapsin response mediating protein-2 (CRMP2) has been identified as an intracellular protein mediating Semaphorin3A (Sema3A), a repulsive guidance molecule. In this study, we demonstrate that cyclin-dependent kinase 5 (Cdk5) and glycogen synthase kinase 3beta (GSK3beta) plays a critical role in Sema3A signalling. In In vitro kinase assay, Cdk5 phosphorylated CRMP2 at Ser522, while GSK3beta did not induce any phosphorylation of CRMP2. Phosphorylation by GSK3beta was exclusively observed in Cdk5-phosphorylated CRMP2, but barely in CRMP2T509A. These results indicate that Cdk5 primarily phosphorylates CRMP2 at Ser522 and GSK3beta secondarily phosphorylates at Thr509. The dual-phosphorylated CRMP2, but not non-phosphorylated or single-phosphorylated CRMP2, is recognized with the antibody 3F4, which is highly reactive with the neurofibrillary tangles of Alzheimer's disease. 3F4 recognized the CRMP2 in the wild-type but not cdk5-/- mouse embryonic brain lysates. The phosphorylation of CRMP2 at Ser522 caused reduction of its affinity to tubulin. In dorsal root ganglion neurones, Sema3A stimulation enhanced the levels of the phosphorylated form of CRMP2 detected by 3F4. Over-expression of CRMP2 mutant substituting either Ser522 or Thr509 to Ala attenuates Sema3A-induced growth cone collapse response. These results suggest that the sequential phosphorylation of CRMP is an important process of Sema3A signalling and the same mechanism may have some relevance to the pathological aggregation of the microtubule-associated proteins.

Dynamic range reduction inspired by photoreceptor physiology

Abstract: A common task in computer graphics is the mapping of digital high dynamic range images to low dynamic range display devices such as monitors and printers. This task is similar to the adaptation processes which occur in the human visual system. Physiological evidence suggests that adaptation already occurs in the photoreceptors, leading to a straightforward model that can be easily adapted for tone reproduction. The result is a fast and practical algorithm for general use with intuitive user parameters that control intensity, contrast, and level of chromatic adaptation, respectively.

Sensitivity of Fit Indexes to Misspecified Structural or Measurement Model Components: Rationale of Two-Index Strategy Revisited

Abstract: In previous research (Hu & Bentler, 1998, 1999), 2 conclusions were drawn: standardized root mean squared residual (SRMR) was the most sensitive to misspecified factor covariances, and a group of other fit indexes were most sensitive to misspecified factor loadings. Based on these findings, a 2-index strategy-that is, SRMR coupled with another index-was proposed in model fit assessment to detect potential misspecification in both the structural and measurement model parameters. Based on our reasoning and empirical work presented in this article, we conclude that SRMR is not necessarily most sensitive to misspecified factor covariances (structural model misspecification), the group of indexes (TLI, BL89, RNI, CFI, Gamma hat, Mc, or RMSEA) are not necessarily more sensitive to misspecified factor loadings (measurement model misspecification), and the rationale for the 2-index presentation strategy appears to have questionable validity.

Scaling the quality of teammates' mental models: equifinality and normative comparisons

Abstract: We tested the impact of teammates' team and task mental model sharedness on team processes and performance using 70 undergraduate teams that completed a series of missions on a PC-based flight simulator. Moreover, we considered how the quality of mental models might moderate such relationships. Team processes were found to partially mediate the relationship between task mental model sharedness and team performance. Although team mental model sharedness failed to exhibit a significant linear relationship with team processes or performance, it did evidence a multiplicative relationship as moderated by the quality of those models. Team processes and performance were better among teams sharing higher-quality team mental models than among teams evidencing less sharedness or who had lower-quality models. Again, team processes partially mediated these relationships. Results are discussed in terms of the equifinality of mental model quality and applications to various team environments. Copyright © 2005 John Wiley & Sons, Ltd.

Hylid frog phylogeny and sampling strategies for speciose clades

Abstract: How should characters and taxa be sampled to resolve efficiently the phylogeny of ancient and highly speciose groups? We addressed this question empirically in the treefrog family Hylidae, which contains > 800 species and may be nonmonophyletic with respect to other anuran families We sampled 81 species (54 hylids and 27 outgroups) for two mitochondrial genes (12S, ND1), two nuclear genes (POMC, c-myc), and morphology (144 characters) in an attempt to resolve higher-level relationships We then added 117 taxa to the combined data set, many of which were sampled for only one gene (12S) Despite the relative incompleteness of the majority of taxa, the resulting trees placed all taxa in the expected higher-level clades with strong support, despite some taxa being > 90% incomplete Furthermore, we found no relationship between the completeness of a taxon and the support (parsimony bootstrap or Bayesian posterior probabilities) for its localized placement on the tree Separate analysis of the data set with the most taxa (12S) gives a somewhat problematic estimate of higher-level relationships, suggesting that data sets scored only for some taxa (ND1, nuclear genes, morphology) are important in determining the outcome of the combined analysis The results show that hemiphractine hylids are not closely related to other hylids and should be recognized as a distinct family They also show that the speciose genus Hyla is polyphyletic, but that its species can be arranged into three monophyletic genera A new classification of hylid frogs is proposed Several potentially misleading signals in the morphological data are discussed

Refractive indices of liquid crystals for display applications

Abstract: This paper reviews the extended Cauchy model and the four-parameter model for describing the wavelength and temperature effects of liquid crystal (LC) refractive indices. The refractive indices of nine commercial LCs, MLC-9200-000, MLC-9200-100, MLC-6608, MLC-6241-000, 5PCH, 5CB, TL-216, E7, and E44 are measured by the Multi-wavelength Abbe Refractometer. These experimental data are used to validate the theoretical models. Excellent agreement between experiment and theory is obtained.

Appearance modeling for tracking in multiple non-overlapping cameras

Abstract: When viewed from a system of multiple cameras with non-overlapping fields of view, the appearance of an object in one camera view is usually very different from its appearance in another camera view due to the differences in illumination, pose and camera parameters. In order to handle the change in observed colors of an object as it moves from one camera to another, we show that all brightness transfer functions from a given camera to another camera lie in a low dimensional subspace and demonstrate that this subspace can be used to compute appearance similarity. In the proposed approach, the system learns the subspace of inter-camera brightness transfer functions in a training phase during which object correspondences are assumed to be known. Once the training is complete, correspondences are assigned using the maximum a posteriori (MAP) estimation framework using both location and appearance cues. We evaluate the proposed method under several real world scenarios obtaining encouraging results.

Sufficient Dimension Reduction via Inverse Regression

Abstract: A family of dimension-reduction methods, the inverse regression (IR) family, is developed by minimizing a quadratic objective function. An optimal member of this family, the inverse regression estimator (IRE), is proposed, along with inference methods and a computational algorithm. The IRE has at least three desirable properties: (1) Its estimated basis of the central dimension reduction subspace is asymptotically efficient, (2) its test statistic for dimension has an asymptotic chi-squared distribution, and (3) it provides a chi-squared test of the conditional independence hypothesis that the response is independent of a selected subset of predictors given the remaining predictors. Current methods like sliced inverse regression belong to a suboptimal class of the IR family. Comparisons of these methods are reported through simulation studies. The approach developed here also allows a relatively straightforward derivation of the asymptotic null distribution of the test statistic for dimension used in slic...

Particle bombardment and the genetic enhancement of crops: Myths and realities

Abstract: DNA transfer by particle bombardment makes use of physical processes to achieve the transformation of crop plants. There is no dependence on bacteria, so the limitations inherent in organisms such as Agrobacterium tumefaciens do not apply. The absence of biological constraints, at least until DNA has entered the plant cell, means that particle bombardment is a versatile and effective transformation method, not limited by cell type, species or genotype. There are no intrinsic vector requirements so transgenes of any size and arrangement can be introduced, and multiple gene cotransformation is straightforward. The perceived disadvantages of particle bombardment compared to Agrobacterium-mediated transformation, i.e. the tendency to generate large transgene arrays containing rearranged and broken transgene copies, are not borne out by the recent detailed structural analysis of transgene loci produced by each of the methods. There is also little evidence for major differences in the levels of transgene instability and silencing when these transformation methods are compared in agriculturally important cereals and legumes, and other non-model systems. Indeed, a major advantage of particle bombardment is that the delivered DNA can be manipulated to influence the quality and structure of the resultant transgene loci. This has been demonstrated in recently reported strategies that favor the recovery of transgenic plants containing intact, single-copy integration events, and demonstrating high-level transgene expression. At the current time, particle bombardment is the most efficient way to achieve plastid transformation in plants and is the only method so far used to achieve mitochondrial transformation. In this review, we discuss recent data highlighting the positive impact of particle bombardment on the genetic transformation of plants, focusing on the fate of exogenous DNA, its organization and its expression in the plant cell. We also discuss some of the most important applications of this technology including the deployment of transgenic plants under field conditions.

Decision tree classifier for network intrusion detection with GA-based feature selection

Abstract: Machine Learning techniques such as Genetic Algorithms and Decision Trees have been applied to the field of intrusion detection for more than a decade. Machine Learning techniques can learn normal and anomalous patterns from training data and generate classifiers that then are used to detect attacks on computer systems. In general, the input data to classifiers is in a high dimension feature space, but not all of features are relevant to the classes to be classified. In this paper, we use a genetic algorithm to select a subset of input features for decision tree classifiers, with a goal of increasing the detection rate and decreasing the false alarm rate in network intrusion detection. We used the KDDCUP 99 data set to train and test the decision tree classifiers. The experiments show that the resulting decision trees can have better performance than those built with all available features.

Variable focus liquid lens

Abstract: A liquid-filled variable focus lens cell is disclosed. The liquid lens cell consists of four parts: a clear distensible membrane, a transparent wall member, liquid with a fixed volume stored in lens cell chamber, and an annular periphery sealing ring. The inner surfaces of the annular sealing ring are sealed with distensible membrane. The radius of the annular sealing ring is changeable, similar to a conventional iris diaphragm. By tuning the radius of the annular sealing ring, the stored liquid in the lens cell will be redistributed, thus change the curvature of the distensible membrane. Therefore, the liquid lens cell can cause light to converge or diverge. The liquid filled lens can be operated mechanically or automatically.